// Copyright (c) 2011 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "base/native_library.h"

#include <windows.h>

#include "base/files/file_util.h"
#include "base/strings/string_util.h"
#include "base/strings/stringprintf.h"
#include "base/strings/utf_string_conversions.h"
#include "base/threading/thread_restrictions.h"

namespace base {

typedef HMODULE(WINAPI* LoadLibraryFunction)(const wchar_t* file_name);

namespace {

    NativeLibrary LoadNativeLibraryHelper(const FilePath& library_path,
        LoadLibraryFunction load_library_api,
        NativeLibraryLoadError* error)
    {
        // LoadLibrary() opens the file off disk.
        ThreadRestrictions::AssertIOAllowed();

        // Switch the current directory to the library directory as the library
        // may have dependencies on DLLs in this directory.
        bool restore_directory = false;
        FilePath current_directory;
        if (GetCurrentDirectory(&current_directory)) {
            FilePath plugin_path = library_path.DirName();
            if (!plugin_path.empty()) {
                SetCurrentDirectory(plugin_path);
                restore_directory = true;
            }
        }

        HMODULE module = (*load_library_api)(library_path.value().c_str());
        if (!module && error) {
            // GetLastError() needs to be called immediately after |load_library_api|.
            error->code = GetLastError();
        }

        if (restore_directory)
            SetCurrentDirectory(current_directory);

        return module;
    }

} // namespace

std::string NativeLibraryLoadError::ToString() const
{
    return StringPrintf("%u", code);
}

// static
NativeLibrary LoadNativeLibraryWithOptions(const FilePath& library_path,
    const NativeLibraryOptions& options,
    NativeLibraryLoadError* error)
{
    return LoadNativeLibraryHelper(library_path, LoadLibraryW, error);
}

NativeLibrary LoadNativeLibraryDynamically(const FilePath& library_path)
{
    typedef HMODULE(WINAPI * LoadLibraryFunction)(const wchar_t* file_name);

    LoadLibraryFunction load_library = reinterpret_cast<LoadLibraryFunction>(
        GetProcAddress(GetModuleHandle(L"kernel32.dll"), "LoadLibraryW"));

    return LoadNativeLibraryHelper(library_path, load_library, NULL);
}

// static
void UnloadNativeLibrary(NativeLibrary library)
{
    FreeLibrary(library);
}

// static
void* GetFunctionPointerFromNativeLibrary(NativeLibrary library,
    StringPiece name)
{
    return GetProcAddress(library, name.data());
}

// static
std::string GetNativeLibraryName(StringPiece name)
{
    DCHECK(IsStringASCII(name));
    return name.as_string() + ".dll";
}

} // namespace base
